fix: potential deadlock #125
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Fixes potential deadlock in containerd#123 Signed-off-by: Steven Kreitzer <[email protected]>
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There were at least two code paths which might acquire `.RLock()` recursively: 1. `Setup*()` -> `createResult()` 2. `Setup*()` -> `Networks()`. On its own, it's not a problem, but if `.Load()` is called concurrently, it might do `.Lock()` in between recursive `.RLock()`s, which would lead to a deadlock. See containerd#125 Fix by introducing a contract on the way mutex is acquired. Add a test facility to verify for such mistakes via build tags: * `go test -race` or `go test -tags deadlocks` activates deadlock detection Signed-off-by: Andrey Smirnov <[email protected]>
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There were at least two code paths which might acquire `.RLock()` recursively: 1. `Setup*()` -> `createResult()` 2. `Setup*()` -> `Networks()`. On its own, it's not a problem, but if `.Load()` is called concurrently, it might do `.Lock()` in between recursive `.RLock()`s, which would lead to a deadlock. See containerd#125 Fix by introducing a contract on the way mutex is acquired. Add a test facility to verify for such mistakes via build tags: * `go test -race` or `go test -tags deadlocks` activates deadlock detection Signed-off-by: Andrey Smirnov <[email protected]>
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| @@ -183,8 +181,6 @@ func (c *libcni) SetupSerially(ctx context.Context, id string, path string, opts | |||
| if err := c.ready(); err != nil { | |||
| return nil, err | |||
| } | |||
| c.RLock() | |||
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I don't think this is totally correct (removing the lock), at least it's not clear if it is, see #126
|
Closing in favor of #126 |
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Fixes siderolabs/talos#9984 Patch with containerd/go-cni#126 See also: * containerd/go-cni#125 * containerd/containerd#11186 * containerd/go-cni#123 Signed-off-by: Andrey Smirnov <[email protected]>
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Fixes siderolabs/talos#9984 Patch with containerd/go-cni#126 See also: * containerd/go-cni#125 * containerd/containerd#11186 * containerd/go-cni#123 Signed-off-by: Andrey Smirnov <[email protected]> (cherry picked from commit 0b00e86)
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This will fix the potential deadlock in #123
I'm not entirely sure why these excess locks were added.
Status()was basically renamed toready(), and thenSetup(),SetupSerially(),Remove(), andCheck()have added the additional lock mutexes below thec.ready(), which were not present with the previousStatus()code.You can see them before the change here:
Status()
ready()
Setup()
and so on...